Now, porphyrias are diseases that
I've described as we went through
this relating to the deficiencies of
enzymes in the synthesis of heme.
They're unusual and they actually have
some interesting historical significance.
They arise from
deficiencies as I said
and the accumulation
of the porphyrins that
arise by the deficiencies
of those enzymes.
Acute porphyrias can cause brain and
nerve problems and can be fatal.
More commonly, however, other porphyrias
involve things like severe abdominal pain,
and mental issues.
And those mental issues
can be unpredictable.
A person could be perfectly normal and then
all of a sudden act in an insane fashion.
And that relates to some historical
significance I'll talk about.
The porphyrias can also arise
from heavy metal poisoning.
One of the enzymes of
the process you recall
was very sensitive to
heavy metals like lead.
This can also arise from
drugs that affect some liver
enzymes that are important for
making these heme molecules.
Now, defects of any heme synthesis enzyme
can give rise to a type of porphyria.
Liver disease can
also cause porphyria.
Now, porphyrias can be manifested and
seen in skin problems that arise
when they accumulate in the skin and
fluoresce as seen in this photo.
Teeth may be deformed in some porphyrias
and discolored as shown here.
Gum and eye abnormalities
are also known.
The skin can be discolored and you
can see some discoloration here.
And some of that discoloration
can go away on exposure
to light because these compounds
are sensitive to light.
And the people who have them
themselves are sensitive to light.
They will avoid light.
Now, the historical significance;
the madness of King George,
the person who is king at the time
the American colonies revolted,
was said to have
intermittent mental issues.
And it was believed that King
George suffered from porphyria
and the madness of King George
was due to a genetic disease.
It is known for example that his
ancestor did have the disease.
Now a more interesting significance
with respect to history,
actually relates to something
that manifests itself in the
types of symptoms that some
people with porphria exhibit.
Remember that some people
have discolored skin
and some people are very
sensitive to light.
And it is thought that
the porphyria may have
been associated with
the vampire legends.
The thought of the vampire legends was
that the people were actually deficient
in hemoglobin and what they
were trying to do is get blood.
Well, in fact, it was actually
the opposite that was happening.
But that doesn't really matter.
What matters is that we have the
vampire legend that may have arisen as
a result of people's misunderstanding
of what happened in porphyria.